I learned something new. I've always been careful when removing the pushrod and seal. On 2 of mine I replaced the clutch pushrod seal and the ball fell out when I had the rod and seal removed and the bike was leaning to the left on the kickstand. Turns out they had smaller diameter balls (same diameter as the pushrod). Must have been done by previous owners.

I'm not familiar enough with the 250/360/400 to definitively know...  but I also remember the ball was the same size as the pushrods on the earlier models with the "worm gear" actuator? 

Thanks for all the responses guys, hopefully I'll be able to get back to the bike this afternoon.  I did order another ball bearing just in case it was MIA.

MarkT said:

but I also remember the ball was the same size as the pushrods on the earlier models with the "worm gear" actuator

I have a '73 RT3 engine dismantled. It has a 5/16" ball.  The ones that fell out were on '71 DT1E 250s. Maybe Yamaha did use both.

Talking 1/4 ball bearing like in the actuator--Hmm, interesting, unless someone had inadvertently lost the ball from the actuator & thought--pushrod is too short so dropped one down ahead of the pushrod. Think i'm responding to #11.

Ok, got up the energy to put the top end back together and confirmed the ball bearing is there.  Thank you guys for all your help, this is the deepest I've been into these bikes, I'll leave the transmission to the pros but I got this

For all interested parties, I installed the new clutch parts (everything except the clutch basket, ball and push rod), and all works as it should now.  Not 100% sure I have the adjuster on the left side cover adjusted correctly, I did install a new adjuster w/nut (was able to find them) but the adjuster is turned in way more that I would think should be.   

The nut is on backwards. The round part of it should face inboard.

Also you won't be able to adjust it properly until you have all the clutch parts installed.

After everything is installed but before putting on the right crankcase cover loosen the adjustment for the cable at the perch.  Then tighten the screw in the actuator so there is no play and back off 1/8 turn. Tighten the nut while keeping the screw from turning. Then take the slack out of the cable at the perch and back off 1/8-1/4 turn. Verify the operation before you put the crankcase cover on and verify operation before you add oil. I verify by working the clutch while in first gear and rolling it. There will be resistance but it should roll. If you put the crankcase cover on and it won't disengage the pressure plate might be hitting the crankcase cover which means things are not installed properly.

I read you have it together assembled with new parts but using the old drum. So it doesn't take much to make a difference at the adjuster, things like the stacked height of new plates or aftermarket plates could do it. I think the main thing is how far from falling out is the 1/4 ball in the actuator. Looks like a brass aftermarket actuator so do they have a ball inserted or is there room for one. Might need to get some 1/4 silver steel & make a rod a few mm longer so it stays shrouded & retained from wobbling by the actuator but with the adjuster backed out to a full nut or a bit more.--if that makes sense!!.

Thank you guys.  I do have it all together and have taken it for a short ride, it just seemed odd that the adjuster was so far adjusted in, I will turn the nut around and readjust.